Cyanoperfluoro(vinyl ethers), their preparation and copolymers thereof

ABSTRACT

Disclosed herein are cyanoperfluoro(vinyl ethers), intermediate acid fluorides; a process for preparing the acid fluorides, and a process for preparing the vinyl ethers from acid fluoride and an alkali-metal carbonate. Also disclosed are copolymers incorporating units derived from the vinyl ethers as crosslinking constituents therein.

Unite States Patent 1 Nottke Dec. 3, 1974 1 1 CYANOPERFLUORO(VINYL ETHERS),

THEIR PREPARATION AND COPOLYMERS THEREGF [75] Inventor: James E. Nottke, Wilmington, Del.

[73] Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

[22] Filed: June 14, 1972 [21] Appl. No.1 262,590

[52] US. Cl. 260/465.6, 260/338 F, 260/8077,

260/855 A [51] llnt. Cl. C07c 121/02, C070 121/30 [58] Field of Search 260/4656 [56] References Cited UNITED STATES PATENTS 4/l964 Lawlor 61 a1 260/4656 x 10/1967 Fritz et ill, U 260/4656 Primary Examiner-Joseph P. Brust [57] ABSTRACT Disclosed herein are cyanoperfluoro(vinyl ethers), in termediate acid fluorides; a process for preparing the acid fluorides, and a process for preparing the vinyl ethers from acid fluoride and an alkalimetal carbonate. Also disclosed are copolymers incorporating units derived from the vinyl ethers as crosslinking constituents therein.

8 Claims, N0 Drawings CYANOPERELUORO(VINYL ETHERS), THEIR PREPARATION AND COPOLYMERS THEREOF BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION The novel process of this invention comprises reacting CF (n 1) CF t 3 IF C0? 3 CN 01 CF 0 perfluord- (m-cyanopr-ohexatluoropionyl) fluoride propylene oxide the invention can contain units derived from 2, 3 or more monomers. Preferred classes of copolymers include terpolymers of the novel vinyl ethers with a. vinylidene fluoride and hexafluoropropylene,

b. tetrafluoroethylene and CF =CFO-R, wherein R, is Perfluoroalkyl of from 1-3 carbons. The most preferred copolymers are those in which the novel polymeric components described herein have values for n of O to 2.

Preferably, the polymers of the invention contain units derived from the cyanopertluoro(vinyl ether) in the amount of about 0.5 to 10 mole percent. In terpolymers, the other eomonomers are from 99.5 to 95 mole percent of the terpolymer, and are preferably present in roughly equal proportions, ranging relative to one another from 30/70 to 70/30, preferably about 50/50 mole percent.

CN CF CN CF cyanoperfluoro viny 1 ether) In the process as outlined, M is an alkali metal, silver, copper (I), mercury (I) or tetra(lower alkyl)ammonium', M is an alkali metal; and n is an integer from 0 to 4. The preferred vinyl ethers are those in which n is from O to 2.

DETAILS OF THE INVENTION The perflu0ro(oz-cyanopropionyUfluoride reactant is made in accordance with the disclosure in the coassigned application entitled Perfluoro(a- Cyanopropionyl) Fluoride And Its Preparation," filed Presented in the Table are the novel products of this 40 concurrently herewith in the name of David C. En-

invention.

TABLE gland, Ser. No. 262,59i.

Acid Fluorides Vinyl Ethers Copolymers normally solid random copolymers of at least one vinyl ether ct polymerized with at least one member of the perfluorot X-eyantr S-methyldb-dioxal-nonene) group vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene.

pert'luorot l7-cyano- 5,8.1 l,l4-tetramethyl- 3,6.9,l2.l5-pentaoxal'octadecene) [where l,l,l.2,3-pentafluoro propylene, and CF =CF-0-R,, where R, is perfluoroalkyl of l to 3 carbons.

Copolymer is used herein in its usual generic sense to mean a polymer containing units derived from at least two monomers. Thus, the polymeric products of In summary, the perfluoro(a-cyanopropionyl) fluoride is made from carbonyl fluoride and perfluoroacrylonitrile at a ratio of at least one mole of carbonyl fluoride per mole of perfluoroacrylonitrile. The reaction is carried out in the presence of an alkali-metalfluoride, silver-fluoride or copper(I)-fluoride catalyst. The reaction is conducted in an inert, aprotic solvent at a temperature from about 40C to 200C. Making the Acid Fluorides It should be understood that a product of this step in which n l is relatively low can be reacted with hexafluoropropylene oxide under the conditions described below to give a product of the same formula but with a higher value of n 1. Likewise, a mixture of compounds having different values of n I can be reacted with hexafluoropropylene oxide under the same conditions to give a product (usually a mixture) having a higher value or values of n l.

Reactant ratios will usually be about that dictated by the stoichiometry of the desired reaction. Even when exact whole-number reactant ratios are used, a mixture of compounds having different values of n usually re-- sults. However, the desired product, which will always predominate, can be separated by distillation. The separation is easier for relatively lower values of n.

Examples of some operable tetra(lower alkyl) ammonium fluoride catalysts are tetramethylammonium fluoride. tetraethylammonium fluoride, tetraisopentylammonium fluoride. tetrahexylammonium fluoride, diethyldipropylammonium fluoride, and heptylhexylmethylpropylammonium fluoride. Lower alkyl is defined as alkyl of up to seven carbons. The preferred catalysts are the alkali-metal fluorides, particularly cesium fluoride because of the good conversions that it gives.

The amount of catalyst can vary widely and can be 7 from about 0.001 to more than 1.0 equivalent per mole of acid fluoride. About 0.01 equivalent to 0.1 equivalent is preferred.

Suitable solvents are the glymes, CH (OCH CH ),,,OCH;,, where m is an integer of at least 1. The compound in which m is l is called glyme; in diglyme, m 2, in triglyme, m 3, in tetraglyme, m 4, and so on. The amount of solvent can vary widely, but generally at least enough is used so that all the catalyst is dissolved in the solvent/acid fluoride mixture. In practice, from about 2 to 10 moles of solvent per equivalent of catalyst are used.

The operable temperature range is from about 30C to 30C. The temperature for a given run will depend considerably on the amount of catalyst, particularly when the preferred catalyst, cesium fluoride, is used. With equivalent amounts of cesium fluoride, the reaction proceeds readily at about -30C to C. With the preferred amounts of cesium fluoride, the preferred temperature range is about 10 to 20C.

The reaction is conveniently run in an open system with suitable condensing means for returning lowboiling materials to the mixture. Closed systems at autogenous pressures can be used but are less convenient. The higher pressures then involved require especially rapid mixing and efficient cooling. Reaction conditions are usually maintained for a period of from a few minutes to an hour after all the hexafluoropropylene oxide is added to insure complete reaction.

Making the Vinyl Ethers The acid fluoride product is mixed with a preheated stream of an inert gas such as nitrogen, helium, or carbon dioxide, and the resulting gaseous mixture is passed through a finely divided alkali-metal carbonate solid in fluidized-bed reactor at between about 200C and 300C. The best conversions to the desired products are obtained between about 225C and 275C. and this temperature range is therefore preferred.

In the fluidized-bed reactor, the solid is fluidized by the gas stream and reacts with the acid fluoride components simultaneously. Elements of carbonyl fluoride are eliminated to produce at least one novel cyanoperfluoro(vinyl ether). The fluidized-bed technique for bringing about reactions of solids with gases is well known to those skilled in the art. See, for example, Fluidization Engineering by D. Kunii and O. Levenspiel (Wiley, 1969).

An amount of alkali-metal carbonate at least equivalent to the acid fluoride is used, and the rate of addition of the acid fluoride is such that all of it reacts before reaching the end of the fluidized bed. To help determine the rate of addition, the composition of the effluent gas can be monitored by gas chromatography or infrared analysis.

Copolymeric Products The novel polymeric products heretofore described can be prepared by any of a number of known processes for making fluorine-containing copolymers. A preferred method, described in more detail in coassigned US. Pat. No. 3,546,186, employs aqueous media and free-radical initiators at slightly elevated temperatures, say, 40C, and pressures in the order of p.s.i.g. Alternatively, bulk or solution processes can be used with appropriate free-radical catalysts.

.Those skilled in the art will be able to determine any DESCRIPTION OF THE PREFERRED EMBODIMENTS The following Examples illustrate the products and process of this invention.

EXAMPLE I Perfluoro(5-cyano-2-methyl-3-oxahexanoyl) ride [major fraction] 00F-COF To a flask containing 8.0 g of cesium fluoride and 30 ml of dry tetraglyme was added 158 g of perfluoro-(acyanopropionyl) fluoride. A dry nitrogen atmosphere and stirring were maintained throughout the reaction. With the reaction temperature maintained at l220C, 149 g of hexafluoropropylene oxide (HFPO) was added at such a rate that a gentle reflux wasmaintained from a dry-ice condenser over the'reaction. The mixture was stirred for 30 minutes at 25C after theiHFPO addition was complete. The volatiles were distilled under vacuum into a dry-ice-cooled flask, leaving the cesium fluoride and tetraglyme in the reaction flask. The collected volatiles were redistilled to give 262.5 g (86%) of perfluoro(5-cyano-2-methyl-3-oxahexanoyl) fluoride, B.R. 739C, and 8.5 g (2.2%) of a 1:1 mixture of this product and perfluoro(8-cyano-2,5 dimethyl-3,-dioxanonanoyl) fluoride, B.R. 8ll24C. The following analytical determinations were made on other samples prepared by essentially the foregoing method.

Anal. Calcd. for C,F,,NO C, 24.79; F, 61.63; Found: C, 25.25; F, 63.82;

Spectral data:

IR (gas): 2295, 1895, 1305,1250, 1170, 1140 1115, and 980 cm". FMR (neat): 26.3 (4 doublets, J 5.5, 5.3Hz,

(2 doublets, J 9.5, 5.5Hz, 3F), -79.5 (multiplet, IF), Xl.9

(4 doublets, J 5.5, 3.0, 1.2Hz,

3F), l3(l (multiplet, 1F), l39 ppm (multiplet, 1F).

EXAMPLE 2 Perfluoro( 8-cyano-2,5-dimethyl-3,6-dioxanonanoyl) Fluoride [major fraction] CIIN CF CFa The procedure was essentially that of Example 1, with some variation in times because of the different amounts of reactants and slight variations in temperature. From 2.5 g of cesium fluoride, ml of tetraglyme, 46 g of perfluoro(a-cyanopropionyl) fluoride, and 90 g of hexafluoropropylene oxide, the following fractions were obtained in the redistillation step, and their compositions were determined by gas chromatography.

F -CF CF 0 ,F-- COP 01L CF 11.R., (3. (1111s. (Composition; :1 in) 01-03 11.5 60% llFlO dimer"; 102,, 11:0 63-70 10.4 75% 11:0, 11:1 110-120 J1. 3 100% 11:1 120/760 100111111 12.5 42% 11:1, 58% 11:11

The products and their yields were therefore as follows: Perfluoro(5-cyano-2-methyl-3-oxahexanoyl) fluoride (n 0), 13%; perfluoro(8-cyano-2,5-dimethyl- 3,6-dioxanonanoyl) fluoride (n l), 75%, and perfluo' ro(1 1cyano-2,5,8-trimethyl-3,6,9-trioxadodecanoyl) fluoride (n 2), 4%.

The infrared absorption spectrum ofthe major product (n l) was essentially superimposable on that of the major product of Example 1, with some differences in intensities and insignificant differences in frequenc1es.

The fluorine magnetic resonance of the major product was determined on a separate sample.

FMR (neat): 1- 26.4 (multiplet, 1F), 75.0 (multiplet, 5F), 79.8 (multiplet, 3F), 824 (multiplet, 3F), 84.0 (multiplet, 2F), -l31 (multiplet, IF),

l45 (multiplet, 1F), -175 ppm (multiplet, 1F). I

EXAMPLE 3 Perfluoro-l l-cyano-2,5,8trimethyl-3,6,9-trioxadodecanoyl Fluoride [major fraction] By essentially the procedure of Examples 1 and 2,7 g of cesium fluoride, ml of tetraglyme, 111.5 g of perfluoro(a-cyanopropionyl) fluoride, 68.5 g of perfluoro-(5-cyano-2-methyl-3-oxahexanoyl) fluoride, and 256 g of hexafluoropropylene oxide were reacted to give, in addition to the products of Examples 1 and 2,

24.1 g of perfluoro-l1-cyano-2,5,8-trimethyl-3,6,9-tri- EXAMPLE 4 Perfluoro( 8-cyar1o5-methy1-3 ,6-dioxal -nonene) [major fraction] CN CF A bed (8 X cm) of finely divided dry sodium can bonate held at 250-270C in a vertical glass tube was fluidized with a minimum flow of preheated (300C) nitrogen from the bottom, and the exit gases passed out the top-through a series of three dry-ice cooled traps. Perfluoro(8-cyano-2,S-dimethyl-3,6-dioxanoanoyl) fluoride (215 g) was added at 0.59 ml/minute to the preheated nitrogen entering the bed. After all of the acid fluoride had been added, the traps were washed out with the aid of ethyl ether and the combined trap contents distilled to give 172 g of perfluoro(8- cyano-5-methyl-3,6-dioxa-l-nonene).

The following analytical data were obtained from separate samples prepared essentially as just described: B.P. -121C, and

Anal. Calcd for C,,F,,NO C, 24.62; F, 64.90; N, 3.19 Found: C, 24156; F, 64.94, N, 3.06

Spectral data:

IR (neat): 2290, 1840, 1450-1100, 1060, 980, 810,

FMR (neat): -75.5 (multiplet, 5F), -80 (multiplet, 3F), 84.5 (multiplet, 2F), 1 15 (2 doublets, J 86, 66.5 Hz, F). l22 (2 doublets J 111, 86 Hz,

EXAMPLE 5 I Perfluoro(5-cyano-3-oxa-l-hexene) of units derived from the perfluoro(8-cyano-5- methyl-3,6-dioxa-1-nonene).

Crosslinking The terpolymer was combined with three corresponding products made in the same manner, and 95 grams of the mixed terpolymers was mixed with 5.7 g of tetraphenyltin on a two-roll rubber mill. Samples were molded under pressure at 177C for different times and then heated in an oven for 24 hours at 204C 0 in air. Tensile testing by the method of ASTM D-4l2- 66 gave the following results, which indicate that the product was crosslinked:

Press Cure time (hrs.) 05 l 2 17 Stress at 10071 elong, M ,,,(psi) 520 490 480 460 Stress at 20071 clung, M l psi) 1370 1440 1275 1350 Stress at break, T (psi) 2325 1900 2460 2380 Elongation at break, E 7r 240 230 260 250 Tensile set, T.S, '7: l3 l2 l4 l3 UTILITY The products of this invention are useful for making crosslinked elastomers. Representative uses for such elastomers are as gaskets, chemical and thermal resistant lining for containers and coating or jacketing for hoses, cables and pipes.

As already stated, units derived from more than one of the novel vinyl ethers can be present in the copolymers of the invention. When two or more vinyl ethers are used as comonomers, they can be added to the copolymerization recipe as predetermined amounts of pure compounds or as an incompletely separated mixture of cyano(perfluoro vinyl ethers). A typical mixture of vinyl ethers is one such as is obtained by reacting the mixture of acid fluorides produced in Example 3 with an alkalimetal carbonate by the method of Examples 4 and 5.

EXAMPLE 6 Terpolymer of tetraflu oroethylene, perfluoro- (methyl vinyl ether), and perfluoro(S-cyano-S- methyl-3,6-dioxa-l-nonene) A 400-ml stainless-steel shaker tube was charged with 100 ml of distilled water under nitrogen. The water was frozen by chilling the tube with solid carbon dioxide, and there were added to the tube under nitrogen l.0 g of ammonium perfluorooctanoate, 0.80'g of ammonium persulfate, 0.20 g of sodium sulfite, 2.5 g of disodium monohydrogen phosphate heptahydrate, and 0 3.0 g of perfluoro(8-cyano-5-methyl-3,6-dioxa-1- nonene). The tube was closed and evacuated while still cold, and there were added 36.0 g of perfluoro(methyl vinyl ether) and 17.0 g of tetrafluoroethylene. The tube and contents were heated at 50C for 8 hours with shaking. The tube was cooled, volatile materials were allowed to evaporate, and the liquid latex was removed. It weighed 135 g.

The solid terpolymer was isolated by adding an equal volume of aqueous 3% magnesium chloride, filtering the solid that precipitated, washing it in a blender with 50% aqueous alcohol, washing with water, and drying. The infrared absorption spectrum indicated that the tetrafluoroethylene/perfluoro-(methyl vinyl ether)/perfluoro(8-cyano-5-methyl-3,6-dioxa-l-nonene) terpoly- 6 mer contained 33.4 mole units derived from perfluoro(methyl vinyl ether) and an estimated 0.7 mole The crosslinked terpolymer was found to be insoluble in fluorocarbon solvents. Uncured (uncrosslinked) terpolymer would dissolve in such fluorocarbon solvents.

CN CF where n is an integer from O to 4.

2. A compound according to claim 1 where n is 0, perfluoro(5-cyano-3-oxa-l-hexene).

Y 3. A compound according to claim 1 wherein n is l, perfluoro(R-cyano-S-methyl-3 ,6-dioxa l -nonene 4. A compound according to claim 1 wherein n is 2, perfluoro( l l-cyano-5,8-dimethyl-3,6,9-trioxa- 1 dodecene).

5. A compound according to claim 1 where n is 3, perfluoro( l4-cyano-5,8,l l-trimethyl3,6,9, l 2-tetraoxal-pentadecene 6. A compound according to claim 1 where n is 4, perfluoro( l 7-cyano-5,8,1 1,l4-tetramethyl-3,6,9,l2,15- pentaoxal -octadecene 7. A process for making a compound according to claim 1 comprising reacting perfluoro(a-cyanopropionyl)-fluoride with one to five moles of hexafluoropropylene oxide per mole of perfluoro(acyanopropionyl) fluoride, in the presence of a fluoride, MF, wherein M is selected from the group alkali metal, silver, copper(l), mercury(l), and tetra(lower alkyl)- ammonium, at a temperature from about 30 to 30C, and forming an acid fluoride, and reacting the acid fluoride with an alkalimetal carbonate of the formula M CO wherein M is an alkali metal, at a temperature from about 200C to 300C.

- 8. A process according to claim 7 comprising reacting the acid fluoride with the alkali-metal carbonate which is in the form ofa fluidized bed, at a temperature from about 255C to 275C. 

1. A CYANOPERFLUORO(VINYL ETHYL) OF THE FORMULA F3C-CF(-CN)-(CF2-O-CF(-CF3))N-CF2-O-CF=CF2 WHERE N IS AN INTEGER FROM 0 TO
 4. 2. A compound according to claim 1 where n is 0, perfluoro(5-cyano-3-oxa-1-hexene).
 3. A compound according to claim 1 wherein n is 1, perfluoro(8-cyano-5-methyl-3,6-dioxa-1-nonene).
 4. A compound according to claim 1 wherein n is 2, perfluoro(11-cyano-5,8-dimethyl-3,6,9-trioxa-1-dodecene).
 5. A compound according to claim 1 where n is 3, perfluoro(14-cyano-5,8,11-trimethyl-3,6,9,12-tetraoxa-1-pentadecene).
 6. A compound according to claim 1 where n is 4, perfluoro(17-cyano-5,8,11,14-tetramethyl-3,6,9,12,15-pentaoxa-1-octadecene).
 7. A process for making a compound according to claim 1 comprising reacting perfluoro( Alpha -cyanopropionyl)-fluoride with one to five moles of hexafluoropropylene oxide per mole of perfluoro( Alpha -cyanopropionyl) fluoride, in the presence of a fluoride, MF, wherein M is selected from the group alkali metal, silver, copper(I), mercury(I), and tetra(lower alkyl)-ammonium, at a temperature from about -30* to 30*C, and forming an acid fluoride, and reacting the acid fluoride with an alkalimetal carbonate of the formula M''2CO3, wherein M'' is an alkali metal, at a temperature from about 200C to 300*C.
 8. A process according to claim 7 comprising reacting the acid fluoride with the alkali-metal carbonate which is in the form of a fluidized bed, at a temperature from about 255*C to 275*C. 